In an air-intake system of an engine, an intake air temperature sensor, a pressure sensor, a valve rotation sensor and the like are attached to the air intake system. Conventionally, these sensors are independently mounted such that an intake air temperature sensor is mounted to an air cleaner, a pressure sensor is mounted to a throttle body, an intake manifold, or a special housing, and a valve rotation sensor is mounted to a throttle body. Since each sensor requires special wiring or a mounting mechanism, wiring becomes complicated, leading to a complicated installation process. In addition, as the FI (fuel injection) engine system prevails, sensors are demanded to be installed in a compact and modular manner. In response to such a demand, those having a unit made up of a pressure sensor and an intake air temperature sensor, mounted to an intake tube on the upstream side of a throttle body have been proposed (see Patent document 1).
Patent document 1: Japanese Patent Application Laid-Open Publication No. H7-260534